1 lb fresh green bean
preferably long thin "French" beans, but any type will work
1/2 yellow onion
large, cut in half top-to-bottom and then into slivers the same size as the beans, next time I'd probably just use the whole onion
1 tbsp water
plus a bit more if you check and the pan seems dry
2 tbsps oyster sauce
comes in a bottle near the Asian foods in any major supermarket; look for Gluten-Free Oyster Sauce if needed.